In recent years, miniature indoor Base Stations (BSs) have attracted great attention for the sake of improvement of performance of wireless communication systems. The miniature indoor BS is a way for simultaneously resolving issues such as extension of a mobile communication network, improvement of a service quality, integration of an indoor network service, and the like. Thus, the development of the miniature indoor BS is now in progress by many developers, and standardization works necessary for this are also in progress even by standardization groups such as 3rd Generation Partnership Project (3GPP), 3GPP2, Institute of Electrical and Electronics Engineers (IEEE) 802.16m, etc.
Miniature indoor BSs, which are commonly referred to as femtocells, can allow users to enjoy a seamless high-speed data service at a low price even indoors without replacement of communication equipments and separate manipulation by installing inexpensive BSs indoors. Particularly, because the miniature indoor BS can provide a user positioned in a service shadow area with a service of the same quality as if an outdoor BS was nearby, it can be said to be an attractive alternative to mobile communication service providers or users.
A femtocell and a macrocell may either operate at the same frequency or operate at different frequencies. In case where the femtocell and macrocell operate at the same frequency, if a Mobile Station (MS) being in communication with a macro BS moves and enters a femtocell area, the MS can receive a signal of the femtocell. Thus, the MS can perform a handover to the femtocell after comparing a receive power of the femtocell signal with a receive power of a macrocell signal and detecting the femtocell area. On the contrary, in case where the femtocell and the macrocell operate at different frequencies, the MS has to scan a signal of the femtocell in order to detect the signal of the femtocell and an area, after changing an operation frequency from the macrocell frequency to the femtocell frequency.
The femtocell can be installed in any position of the macrocell. Moreover, a lot of femtocells can be also installed. Thus, the MS should perform scanning at all available femtocell frequencies at all times even in any position within the macrocell. Inter-frequency scanning deteriorates communication performance of an MS, which is in a connected mode state of transmitting/receiving a signal with a macro BS. Also, the inter-frequency scanning causes an increase of power consumption of an MS, which is in an idle mode state of transmitting/receiving no signal. In addition, the femtocell may not permit an access of at least one specific MS. Accessible MSs are predefined for every femtocell. To be aware of possibility or impossibility of access to the femtocell, the MS should read an SIB of the femtocell and thus, has to secure sufficient scanning time. In case where the femtocell and the macrocell operate at different frequencies as above, there is a problem of deteriorating communication performance of an MS being in access to a macrocell and, simultaneously, causing an increase of power consumption of the MS. Further, in case where the macrocell and the femtocell not only use different frequencies but also use different Radio Access Technologies (RATs), the MS communication performance deterioration and power consumption problem gets more serious because the MS has to perform both the inter-frequency scanning and inter-RAT scanning. Thus, there is a need to propose an alternative for solving the above problems and facilitating detection of a femtocell and reception of an SIB of the femtocell.